FORT MYERS, Fla. — A few autograph seekers arrived at JetBlue Park around 8:30 a.m. Wednesday and camped out near the practice fields. They sat beside small collections of Red Sox jerseys, bats, and baseballs and kept a close eye on the stadium’s back entrance.

At 10 a.m., they caught a glimpse of the player they came to see: Rusney Castillo, the Red Sox’ new $72.5 million outfielder.

“From everything we’ve read, he’s supposed to be the next big thing,” said Mark Guild, who drove an hour from his home in Venice to see Castillo. “I try to get a bat, a ball, and a jersey of each player. I have Big Papi, Pedro [Martinez], [Dustin] Pedroia. It’d be nice to have Castillo on my wall.”

Castillo, 27, walked into the main building with a wave toward the small group of fans, then 80 minutes later he emerged, all business, wearing a cap and a bright-red, long-sleeved workout shirt in 90-degree weather.

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Ready to work and eager to break a sweat, he surprised some onlookers with his small stature. Others took note of his muscular build. Since defecting from Cuba last December, Castillo has gained 20 pounds, and he took to the JetBlue practice fields at 5 feet 9 inches, 205 pounds.

The nearly 90-minute workout started with a series of stretches, including some dynamic moves where he swung his knees and legs high. He jogged forward and backward, but never came close to the top speeds that impressed scouts. Before he left Cuba, Castillo played in the country’s top league, Serie Nacional, and was among the better base stealers.

After a 20-minute warm-up, Castillo played catch with Red Sox official Laz Gutierrez, tossing the ball over progressively longer distances. As Gutierrez backed farther and farther away, Castillo completed each throw with ease. For now, Gutierrez said, the goal is “just getting him going, ramping him up.”

While mostly serious throughout the stretching and throwing, Castillo flashed a broad smile beneath his sunglasses on a few occasions. And he appeared to get along well with the Spanish-speaking members of the Red Sox organization, sharing some jokes.

“He’s good,” said Gutierrez, the Sox’ player development programs coordinator. “He’s a great kid, a blue-collar guy. He’s a humble guy that loves the game and is ready to work.

“He definitely understands what he’s got himself into. He knows the responsibility that comes with that. He works his tail off. He wants to do well. He wants to be a good representative of the Boston Red Sox.”

As the workout continued, the number of fans watching grew to nearly a dozen. They were curious about a player who could potentially be the next Red Sox star.

Leaving the practice field for the batting cages, Castillo spent about 10 minutes signing autographs and posing for pictures. In a good sign for Red Sox Nation, he seemed to enjoy the attention. To fans who shouted, “Good luck,” he said, “Thank you.”

Other than that, he received instructions from coaches in Spanish and interacted most with Spanish-speaking fans.

When Taylor Cresswell of nearby Cape Coral had a chance to share a few words with Castillo, he said, “Good to see you’re in the US now and ready to play baseball.” Castillo smiled and said, “Thank you.”

“I’m a baseball fan,” said Cresswell. “Seeing a big professional like this who signs for $72.5 million, to be able to shake his hand, is an experience. I know he’s going to be the next big thing.”

Miguel Silva, also of Cape Coral, came with a handful of Castillo action photos that the ballplayer liked. Speaking in Spanish, Silva asked Castillo which photo was his favorite. Castillo picked a photo of himself fielding a ball and Silva promised to bring back a copy Thursday.

Following the impromptu autograph session, the workout finished with 30 minutes in the batting cages, where Castillo worked on his swing and received a respite from the intense sun. After batting practice, Castillo made sure a young girl got a bat he used.

Gutierrez expects Castillo to go through a similar workout Thursday.

When asked how soon Castillo would play in a game, Gutierrez shrugged and said he didn’t know. But he’s one workout closer to shedding his practice gear and putting on a uniform.

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